context_tracking, rcu: Rename rcu_dyntick trace event into rcu_watching

The "rcu_dyntick" naming convention has been turned into "rcu_watching" for
all helpers now, align the trace event to that.

To add to the confusion, the strings passed to the trace event are now
reversed: when RCU "starts" the dyntick / EQS state, it "stops" watching.

Signed-off-by: Valentin Schneider <[e-mail]>
Reviewed-by: Frederic Weisbecker <[e-mail]>
Signed-off-by: Neeraj Upadhyay <[e-mail]>

include/trace/events/rcu.h

···
 /*
  * Tracepoint for dyntick-idle entry/exit events.  These take 2 strings
  * as argument:
- * polarity: "Start", "End", "StillNonIdle" for entering, exiting or still not
- *            being in dyntick-idle mode.
+ * polarity: "Start", "End", "StillWatching" for entering, exiting or still not
+ *            being in EQS mode.
  * context: "USER" or "IDLE" or "IRQ".
  * NMIs nested in IRQs are inferred with nesting > 1 in IRQ context.
  *
  * These events also take a pair of numbers, which indicate the nesting
  * depth before and after the event of interest, and a third number that is
- * the ->dynticks counter.  Note that task-related and interrupt-related
+ * the RCU_WATCHING counter.  Note that task-related and interrupt-related
  * events use two separate counters, and that the "++=" and "--=" events
  * for irq/NMI will change the counter by two, otherwise by one.
  */
-TRACE_EVENT_RCU(rcu_dyntick,
+TRACE_EVENT_RCU(rcu_watching,
 
-	TP_PROTO(const char *polarity, long oldnesting, long newnesting, int dynticks),
+	TP_PROTO(const char *polarity, long oldnesting, long newnesting, int counter),
 
-	TP_ARGS(polarity, oldnesting, newnesting, dynticks),
+	TP_ARGS(polarity, oldnesting, newnesting, counter),
 
 	TP_STRUCT__entry(
 		__field(const char *, polarity)
 		__field(long, oldnesting)
 		__field(long, newnesting)
-		__field(int, dynticks)
+		__field(int, counter)
 	),
 
 	TP_fast_assign(
 		__entry->polarity = polarity;
 		__entry->oldnesting = oldnesting;
 		__entry->newnesting = newnesting;
-		__entry->dynticks = dynticks;
+		__entry->counter = counter;
 	),
 
 	TP_printk("%s %lx %lx %#3x", __entry->polarity,
 		  __entry->oldnesting, __entry->newnesting,
-		  __entry->dynticks & 0xfff)
+		  __entry->counter & 0xfff)
 );
 
 /*

kernel/context_tracking.c

···
 
 	instrumentation_begin();
 	lockdep_assert_irqs_disabled();
-	trace_rcu_dyntick(TPS("Start"), ct_nesting(), 0, ct_rcu_watching());
+	trace_rcu_watching(TPS("End"), ct_nesting(), 0, ct_rcu_watching());
 	WARN_ON_ONCE(IS_ENABLED(CONFIG_RCU_EQS_DEBUG) && !user && !is_idle_task(current));
 	rcu_preempt_deferred_qs(current);
 
···
 	// instrumentation for the noinstr ct_kernel_enter_state()
 	instrument_atomic_write(&ct->state, sizeof(ct->state));
 
-	trace_rcu_dyntick(TPS("End"), ct_nesting(), 1, ct_rcu_watching());
+	trace_rcu_watching(TPS("Start"), ct_nesting(), 1, ct_rcu_watching());
 	WARN_ON_ONCE(IS_ENABLED(CONFIG_RCU_EQS_DEBUG) && !user && !is_idle_task(current));
 	WRITE_ONCE(ct->nesting, 1);
 	WARN_ON_ONCE(ct_nmi_nesting());
···
 	 * leave it in non-RCU-idle state.
 	 */
 	if (ct_nmi_nesting() != 1) {
-		trace_rcu_dyntick(TPS("--="), ct_nmi_nesting(), ct_nmi_nesting() - 2,
+		trace_rcu_watching(TPS("--="), ct_nmi_nesting(), ct_nmi_nesting() - 2,
 				  ct_rcu_watching());
 		WRITE_ONCE(ct->nmi_nesting, /* No store tearing. */
 			   ct_nmi_nesting() - 2);
···
 	}
 
 	/* This NMI interrupted an RCU-idle CPU, restore RCU-idleness. */
-	trace_rcu_dyntick(TPS("Startirq"), ct_nmi_nesting(), 0, ct_rcu_watching());
+	trace_rcu_watching(TPS("Endirq"), ct_nmi_nesting(), 0, ct_rcu_watching());
 	WRITE_ONCE(ct->nmi_nesting, 0); /* Avoid store tearing. */
 
 	// instrumentation for the noinstr ct_kernel_exit_state()
···
 		instrumentation_begin();
 	}
 
-	trace_rcu_dyntick(incby == 1 ? TPS("Endirq") : TPS("++="),
+	trace_rcu_watching(incby == 1 ? TPS("Startirq") : TPS("++="),
 			  ct_nmi_nesting(),
 			  ct_nmi_nesting() + incby, ct_rcu_watching());
 	instrumentation_end();